Fluid overload in the early postoperative period was associated with higher mortality and morbidity. Risk factors for fluid overload include underlying kidney dysfunction, hemodynamic instability, and higher blood loss on the day of the surgery.
The autonomic nervous activity was assessed following supramaximal exercise through heart rate (HR) and blood pressure (BP) variability (HRV and BPV) and baroreflex sensitivity (BRS). The beat-to-beat HR and BP were recorded during the supine and standing states before (PRE) and at 60 (R60) and 120 min (R120) following single (one Wingate, 1W) and multiple sprint intervals (four Wingates interspersed with 4 min of light cycling, 4W). The supine low frequency (LF) component was increased (P<0.001) and the high frequency (HF) was reduced (P<0.01) at R60 (LF, 178.1 ± 11.0; HF, 74.8 ± 10.5) compared with PRE (LF, 140.2 ± 7.4; HF, 110.4 ± 7.2) after both exercises. Supine systolic BPV LF:HF was higher at R60 (4.6 ± 1.4) compared with PRE (6.8 ± 2.4) only after 4W (P=0.035). Supine BRS was lower (P<0.001) at R60 (6.8 ± 1.1) than at PRE (15.3 ± 1.8) and R120 (11.3 ± 1.3). BRS at R120 remained lower after 4W (P=0.02). Standing BRS was less (P<0.001) at R60 (2.3 ± 0.5) than at PRE (5.6 ± 0.8) or R120 (3.7 ± 0.6) and returned to PRE values only after 1W. We concluded that (a) autonomic balance is shifted to a greater sympathetic and less parasympathetic activation following both types of exercise, (b) it takes longer than 1 h to recover following supramaximal exercise and (c) the recovery is longer after 4W than 1W.
The effects of physical exercise stress on the endocannabinoid system in humans are almost unexplored. In this prospective study, we investigated in a crossover design and under field conditions at different altitudes the effects of physical exercise on the endocannabinoid system (ECS) in 12 trained healthy volunteers. For determination of alterations on the ECS three different protocols were analyzed: Protocol A (physical exercise at lower altitude) involved strenuous hiking below 2,100 m, whereas Protocol B (physical exercise by active ascent to high altitude) involved hiking up to 3,196 m, an accommodation at the cottage and a descent the next day. Protocol C (passive ascent) included a helicopter ascent to 3,196 m, an overnight stay at this altitude and a flight back to the base camp the following day. The cumulative hiked altitude in Protocol A and B was comparable (~1,650 m). The blood EC concentrations of anandamide increased significantly in Protocol A/B from baseline (T0) 0.12 ± 0.01/0.16 ± 0.02 (mean ± SEM) to 0.27 ± 0.02/0.42 ± 0.02 after exercise (T1) (p < 0.05). Anandamide levels in Protocol C remained stable at 0.20 ± 0.02. We conclude that the ECS is activated upon strenuous exercise whereas the combination with hypoxic stress further increases its activity. The reduced partial pressure of oxygen at high altitude alone did not affect this system. In summary, physical exercise activates the endocannabinoid system, whereas the combination with high altitude enhances this activation. This discloses new perspectives to adaptation mechanisms to physical exercise.
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